1. Field of the Invention
The present invention relates to an internal combustion engine, and more specifically to an engine equipped with a mechanical governor for holding an engine revolution speed at a predetermined value though an engine load varies as well as a decompression device for decreasing a starting torque at the time of starting operation of the engine.
2. Description of the Related Arts
As such an engine known by the inventors of the present invention, there has been provided the one having the following construction.
That is, a valve actuating camshaft and a governor shaft are arranged in parallel with a crankshaft. The valve actuating camshaft is interlockingly connected to the crankshaft through a valve actuating cam gear, and the governor shaft is interlockingly connected to the crankshaft through a governor gear. A centrifugal weight of the decompression device is supported by one of the opposite side surfaces of the valve actuating cam gear so as to be swingable in the centrifugal direction [for example, refer to U.S. Pat. No. 4,610,227 (Nakano et al.) allowed to the assignee of the present invention]. A governor weight of a mechanical governor is supported by the governor shaft.
In the above-mentioned prior art, when the mechanical governor and the decompression device are installed to the engine, it is necessary to arrange two shafts of the governor shaft and the valve actuating camshaft. Therefore, the engine can't help becoming large in overall dimension.
On one hand, in the case that the engine is intended to be made smaller in overall dimension in the above-mentioned construction of the prior art, it is necessary to make both the centrifugal weight of the decompression device and the governor weight smaller in size in order to avoid an interference therebetween. Thereupon, the decompression device provides a small centrifugal force for cancellation of the decompression and the decompression capability thereof can't help becoming small correspondingly. Also the mechanical governor provides a small governor force and the governor capability thereof is lowered.